The ever increasing amount of rubbish produced by our society leads to ever more severe burdening of the environment. An important factor in overcoming the problems involved is the recycling of waste. One known means of recycling such substances into the natural circuit is the biological utilization of organic matter occurring as waste (such as plant and animal residues) or present as contaminants in matter (such as xenobiotics as harmful substances in earth).
Any such treatment should offer a quick, safe, low-power way of making renewed use of the matter treated, above all without any hazards to the environment. In present day biological waste treatment, however, these aims are reached only insufficiently. That is true particularly of the biological treatment of contaminated soil and the like, where neither the process conditions in existing plants are the best nor is the exclusion of ecological risks guaranteed. In the decontamination of soil, a basic distinction is made between handling methods of the material in its natural ground compound (in-situ) or after excavation of the earth (ex-situ). The ex-situ methods can be applied either on site or off site. The material is placed on a base which is sealed in downward direction to prevent any further contamination. And it is put in an enclosure (tent, building) for protection against the emission of gases exiting from such soils. The exhaust air in part is filtered before it gets back into the atmosphere.